The present application relates to novel activators for catalysts in particular to novel activators for catalysts useful for the polymerization of olefins.
The use of activators or cocatalysts for olefin polymerization-catalysts is well known. For example aluminium alkyls have been used with Ziegler catalysts while aluminoxanes have been used widely with well-defined single site catalysts, for example metallocene catalysts.
The choice of activator for a commercial catalyst depends on many parameters, including performance, cost, safety and stability. There is therefore a need to widen the range of catalyst activators available for use with olefin polymerisation catalysts.
WO 93/13140 describes a catalyst system comprising a modified monocyclopentadienyl transition metal/aluminoxane catalyst system in which a modifier is used having a Lewis Base functionality for example an alkoxysilane. WO 94/20506 describes a method for carrying out a secondary hydrolysis on an aluminoxane to provide a new material having a specific viscosity.
We have now found a class of silicon containing compounds which may be used as activators for olefin polymerization catalysts in particular for use with metallocene catalysts.